This invention relates to a trimmer impedance component, a semiconductor device and a trimming method and relates, in particular, to a semiconductor device with a built-in high-speed element as one example and laser trimming that is a trimming method for obtaining a high-accuracy resistance value.
In general, the resistance value of a resistor formed through semiconductor processes disadvantageously has its absolute value varied by about ±10% due to the influences of variations in processing heat treatment, variations in the implantation energy and dosage during ion implantation and variations in processing dimensions (particularly linewidth) attributed to a photoetching process.
The variations in the resistance value of the resistor disadvantageously directly influence the output voltage and so on of the semiconductor device. Therefore, in the semiconductor device that requires a high-accuracy output voltage, trimming is carried out so that the resistor comes to have the desired resistance value by zener-zap trimming, metal-fuse trimming or laser trimming.
Conventionally, with regard to a semiconductor integrated circuit, a technique for providing a built-in trimming circuit employing a component such as a fuse component programmable after manufacturing so as to enable the adjustment of the generated voltage of a constant-voltage power supply circuit or the like internally provided.
The conventional trimming circuit has had a system in which the trimming has been unidirectionally carried out from a low voltage to a high voltage or from a high voltage to a low voltage. Therefore, even in the presence of processing variations, the trimming has been carried out by providing a design such that the generated voltage has become surely higher (or lower) than the expected value in a non-trimmed state and determining the fuse component that should be cut in the trimming circuit according to the amount of deviation from the expected value by measuring the generated voltage after the manufacturing.
Therefore, almost all the semiconductor integrated circuit products provided with constant-voltage power supply circuits capable of adjusting the generated voltage have been subjected to trimming, and the trimming cannot be recovered once the trimming is carried out. For the about reasons, there is a concern that the product might be defective through the re-measurement after the trimming. In order to avoid this occurrence, a method for making a gradual approach to the expected value by repeating the measurement and trimming again and again cannot help being taken, and time required for the trimming has been long.
Accordingly, in order to cope with this, a technique described in, for example, JP 11-338560 A is proposed. For example, as shown in FIG. 5, a differential amplifier circuit (operational amplifier) 121 is employed as a non-inverted amplifier circuit in a constant-voltage power supply circuit 120 provided in a semiconductor integrated circuit, and a reference voltage Vref from a reference voltage generator circuit 110 is applied to the non-inverted input terminal of the operational amplifier 121. Moreover, a voltage obtained by dividing the output voltage by means of resistors is fed back from a resistance divider circuit 123 to the inverted input terminal of the operational amplifier 121.
This resistance divider circuit 123 has resistance dividing resistors R1 and R2 connected in series and a trimming circuit 124. This trimming circuit 124 enables the adjustment of the generated voltage by having a constitution that a plurality of paired trimmer components, each of which consists of trimmer resistor r11 and program component or switching component such as fuse component F11 connected in series, are connected parallel to each of the resistance dividing resistors R1 and R2. According to this trimming circuit 124, the generated voltage can be adjusted in either the direction in which the voltage is raised or the direction in which the voltage is lowered.
The trimmer resistor for trimming the generated voltage of the constant-voltage power supply circuit 120 or the like has often been applied to a portion through which a high-frequency signal does not pass. That is, the trimming circuit 124, which employs the trimmer resistors, has merely adjusted the generated voltage with regard to the DC (direct current) characteristic by trimming with resistors and has not taken the high-frequency characteristics (AC characteristics) of the trimmer resistors and the fuse components into consideration. For example, in the aforementioned semiconductor integrated circuit, a p-type diffusion layer formed on an n-type epitaxial layer is cut, so that a parasitic capacitance between the n-type epitaxial layer and the p-type diffusion layer (trimmer resistors) changes depending on the portion trimmed, and the characteristics to the high-frequency signal change, disadvantageously causing a harmful influence of, for example, phase shift.